五、三峡工程施工技术、施工机械及建材的研究三峡工程工程量大，施工复杂，“七五”期间着重研究了下列几个重大关键问题：1、二期深水土石围堰的围堰结构型式及施工技术。对围堰主要填筑材料——风化砂的物理、化学、力学性质及深水抛填后的密度、自然坡角、防渗墙结构采用刚 V. Research on Construction Technology, Construction Machinery and Building Materials of the Three Gorges Project The Three Gorges Project is a large project with complex construction. During the “Seventh Five-Year Plan” period, the following key issues were studied emphatically: The cofferdam type of deep-water rock-cofferdam in Phase 1 and Phase 2 And construction technology. On the cofferdam main filling material - weathered sand physical, chemical, mechanical properties and density after throwing the deep water, natural slope angle, cut-off wall structure using just